Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality, ranking fourth as the leading cause of death in the United States. COPD is characterized by reduced maximum expiratory flow, which does not change over several months and which persists for 2 or more consecutive years. Patients with the most severe form of COPD generally have with a significant degree of emphysema. Emphysema is defined anatomically by permanent airspace enlargement distal to the terminal bronchioles. It is characterized by gradual loss of lung recoil, alveolar destruction, decreased alveolar surface area and gas exchange. These two features, impaired gas exchange and reduction in expiratory flow, are characteristic physiological abnormalities from which patients with emphysema suffer. The main symptom of patients with severe emphysema is shortness of breath during minimal physical activity.
The most common cause of emphysema is cigarette smoking although other potential environmental toxins may also contribute. These various toxins activate destructive processes in the lung including release of active proteases and free radical oxidants in excess of protective mechanisms. The imbalance in protease/anti-protease levels leads to destruction of the elastin matrix, loss of elastic recoil, tissue damage and continuous decline in lung function. Removing the injurious agents (i.e. quit smoking) slows the rate of damage, however, the damaged alveolar structures do not repair and lung function is not regained.
COPD is now characterized as a complex inflammatory disease attributed to the inappropriate stimulation of the immune system, especially the activation of T lymphocytes (“T-cells”). Mature T cells can be divided broadly into two functional categories by the presence of two mutually exclusive antigens on their cell surface, CD4 and CD8. While CD8+ T cells are associated with cytotoxicity functions, CD4+ T cells are associated with helper function and secrete various cytokines that regulate and modulate immune responses. CD4+ T cells can be further subdivided into T helper 1 (Th1) and T helper 2 (Th2) subsets, according to the profile of cytokines they secrete. While Th1 cells produce predominantly cytokines such as IL-2, TNF-α and IFN-γ, Th2 cells produce such cytokines as IL-4, IL-5, IL-10, and IL-13. In sum, COPD is a disease that involves various Inflammatory cells, cytokine, chemokine, and other mediators (Jaffery et al. 2001).
Studies of lung tissues of patients with COPD have found an increased number of CD8+ lymphocytes. It has also been suggested that T cells in COPD are predominately type I T cytotoxic (Tc1) cells that produce cytokines like IFN-γ (O'Shaunessey et al.; Corsio et al. 1999; Bouchet et al. 1999). Such findings are further supported by the reports that an increased number of CD3+, CD8+, and CXCR3 (+) cells producing IFN-γ and increased levels of the IFN-γ target gene, IP-10/CXC10, are found in biopsies from patients with COPD (Panzer et al., 2003; Sietta et al. 2002). In addition, studies from the inventors' laboratory demonstrated that transgenic overexpression of IFN-γ in the adult murine lung causes pulmonary emphysema.
IFN-γ is an important component of the inflammatory response and resultant pathology of those diseases exhibiting an inflammatory response. IFN-γ was originally defined based on its anti-viral capacities (Schroeder et al.). It is now, however, appreciated to be an essential immune regulator and the proteotypic Th1 cytokine that plays a key role in diverse biologic responses including pathogen recognition, antigen processing and presentation, regulation of cellular proliferation, induction of apoptosis, activation of microbicidal effector functions, immunomodulation and leukocyte trafficking (Schroeder et al.). In keeping with its important biologic effector functions and key role in Th1 immunity, dysregulated induction of IFN-γ has been implicated in a number of diseases including atherosclerosis, autoimmune disorders (Gagliardo et al.), Chron's Disease (Abreu et al.; Bouma et al.), sarcoidosis (Moeller et al.), microbacterial disease (Winn papers), celiac disease (Lund et al., 2003), rheumatoid arthritis (Chae et al., 2004; Vervoordeldunk et al., 2002), periodontal disease, Baechet's Disease (Ben Ahmed et al., 2004), apthous ulcers (Borra et al.), autoimmune gastritis (Katakai et al., 2003), glemoleftridis (Matsutoni et al., 2003) and uveoritinitis (Foxman et al.). An interesting feature of many of these responses is the close approximation of Th1 inflammation and tissue remodeling characterized by tissue atrophy and/or destruction. This is readily appreciated in the joint erosions in rheumatoid arthritis, ulcerations in Baechet's and apthous ulcers (Borra et al.; Ben Ahmed et al.), tissue remodeling in periodontal disease, ocular destruction and scarring in uveoritinitis (Foxman et al.), clarification and purification in Chron's Disease (Lund et al.; Bouma et al.), myocardial injury in myocarditis (Song et al., 2003) and renal injury in ANCA-associated glemerolinfridis (Masutani et al., 2003). In keeping with the importance of IFN-γ as an immune regulator, an impressive body of work has been dedicated to understanding the mechanisms of regulation of IFN-γ production and its immune effector functions (see review by Schroeder et al.). Surprisingly, even though it is now appreciated that Th1 responses induce tissue injury with minimal healing (Sandler et al.), the mechanisms of this injury and tissue remodeling have not been adequately investigated.
While IFN-γ is thought to be one of the major mediators in the Th1 inflammation, two prominent cytokines, IL-4 and IL-13, are believed to play an important role in the inflammation and airway remodeling of COPD through Th2 inflammatory pathway. IL-4 and IL-13 are similar in that they are both produced by the same subset of Th2 helper T cells, have overlapping effector profiles, and share a receptor component and signaling pathways. However, the critical role of IL-13 over IL-4 in AHR, eosinophil recruitment, mucus overproduction, and other symptoms of asthma has been conclusively demonstrated (Wills-Karp, 1998, Science 282:2258-2260, Grunig et al. 1998, Science 282:2261-2263). Overexpression of IL-13 in the murine lung results in eosinophil, lymphocyte, and macrophage rich inflammation, mucus metaplasia, airway fibrosis, and AHR after methacholine challenge (Zheng et al., 1999 J. Clin. Invest. 103:779-788). Further, polymorphisms in both the IL-13 promoter and the coding region have been associated with the asthmatic phenotype (Heinzmann et al., 2000, Hum. Mol. Genet. 9:549-559). These results suggest that abnormal IL-13 production is a critical component of asthmatic inflammation and airway remodeling.
The role of IL-13 in inflammatory pulmonary diseases is not limited to asthma. COPD has long been thought of as a distinct disease from asthma. However, the similarities between the two diseases have been noted and have resulted in the formulation of the “Dutch Hypothesis”, that was first proposed in 1961. The most recent revision of the Dutch Hypothesis proposes that asthma and COPD, in some individuals, are not distinct processes, and that common pathogenic mechanism underlie these disorders. The hypothesis further states that a genetic predisposition to develop atopy, asthma, AHR and/or increased levels of IgE predispose cigarette smokers to develop COPD (Vestbo and Prescott, 1997, Lancet 350:1431-1434). Further, overexpression of IL-13 in the murine lung causes emphysema and COPD-like mucus metaplasia, IL-13 is overexpressed in biopsy and autopsy lung tissue from patients with COPD, and polymorphisms of IL-13 have been described that correlate with the presence of COPD. When these results are viewed in light of the Dutch Hypothesis, not only are asthma and COPD more closely related than previously thought, but the central role of IL-13 dysregulation in these pulmonary inflammatory disorders becomes more prominent.
In addition to cytokines, another class of inflammatory mediators, chemokines, are believed to also play an important role in Th1 and TH2 mediated immune and inflammatory responses. The chemokine superfamily can be divided into two main groups exhibiting characteristic structural motifs, the Cys-X-Cys (C-X-C) and Cys-Cys (C-C) families. The C-X-C chemokines include several potent chemoattractants and activators of neutrophils such as interleukin-8 (IL-8) and neutrophil-activating peptide 2 (NAP-2). The C-C chemokines include potent chemoattractants of monocytes and lymphocytes but not neutrophils such as human monocyte chemotactic proteins 1-3 (MCP-1, MCP-2 and MCP-3), RANTES (Regulated on Activation, Normal T Expressed and Secreted), eotaxin and the macrophage inflammatory proteins 1α and 1β (MIP-1α and MIP-1β).
Studies have demonstrated that the actions of the chemokines are mediated by subfamilies of G protein-coupled receptors, among which are the receptors designated CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, CCR10, CXCR1, CXCR2, CXCR3 and CXCR4. CCR5 is a receptor that binds MIP-1α/CCL3. and MIP-1β/CCL4 and RANTES/CCL5 (Allgood et al.). It is expressed on granulocytes, dendritic cells, macrophages, CD8+ cells, memory CD4+ cells and at high levels on Th1 lymphocytes (Kunkel et al., 2002; Allgood et al.). CCR5 is predominantly expressed in lymphocytes and macrophages (Wu et al., 1997; Bleul et al., 1997). CCR5 plays a critical role in Th1 inflammation and immunity where it is required for successful irradication/control of a variety of infectious agents such as tuberculosis, Cryptococcus and toxoplasma (Santucci et al.; Hoffnagle et al., 1999; Fraziano et al., 1999; Allgood et al.) and is expressed in exaggerated quantities in Th1-dominated responses including those in tuberculosis, sarcoidosis, Wegner's granulomatosis, rheumatoid arthritis, periodontitis and acute and chronic allograft rejection (Santucci et al.; Frasiano et al.; Katcher et al.; Zhu et al.; Johnston et al.; Nissin et al.; Garulet et al.; Luckow et al.). In these responses, CCR5 plays an important role in the pathogenesis of tissue inflammation and in allograft rejection. It also plays a critical role in the regulation of protease production and tissue remodeling (Luckow et al.). CCR5 may also be involved in local cell death responses and CCR5 serves as a death receptor in neural tissues (Cartier et al. 2003). Despite its frequent co-expression with IFN-γ and its important roles in inflammation, protease production and apoptosis, the role of CCR5 in the pathogenesis of IFN-γ-induced inflammation and tissue remodeling has not been formally investigated.
Because of the critical role chemokines play in various immune and inflammatory diseases, there is ongoing in the art a substantial investigation of different classes of modulators of CCR5. A representative disclosure is Mills et al. WO 98/25617 relating to substituted aryl piperazines as modulators of chemokine receptor activity. Further disclosures are: WO 98/025605; WO 98/025604; WO 98/002151; WO 98/004554; WO 97/024325, WO 00/38680, WO 00/39125, U.S. Pat. No. 6,689,783 (aryl oxime-piperazine derivatives), U.S. Pat. No. 6,689,765 (piperazine derivatives), U.S. Pat. No. 6,602,885 (piperidine derivatives), (U.S. Pat. No. 6,562,859 (pyrrole derivatives), U.S. Pat. No. 6,531,484 (pyrrolidine derivatives), U.S. Pat. No. 6,235,771 (anilide derivatives), U.S. Pat. No. 6,242,459 (bis-acridines), U.S. Pat. No. 6,515,027 (benzanilides), U.S. Pat. No. 6,528,625 (anti-CCR5 antibodies), U.S. Pat. No. 6,100,087 (Ribozymes). However, no attempts have been made to examine in vivo the potential therapeutic effects of CCR5 antagonists in Th1 and Th2 mediated diseases.